Stable library from PyPi:
sudo pip install pms5003
Latest/development library from GitHub:
git clone https://github.com/pimoroni/pms5003-python
cd pms5003-python
sudo ./install.sh
The serial port on your Raspberry Pi must be enabled:
# Disable serial terminal over /dev/ttyAMA0
sudo raspi-config nonint do_serial 1
# Enable serial port
raspi-config nonint set_config_var enable_uart 1 /boot/config.txt
And additionally be using a full UART (versus the default miniUART):
Add the line dtoverlay=pi3-miniuart-bt
to your /boot/config.txt
This will switch Bluetooth over to miniUART, see https://www.raspberrypi.org/documentation/configuration/uart.md for more details.